Orateur
Description
Modern nuclear theory provides insights into the mechanisms of nuclear fission and increasingly allows quantitative predictions. Many observables of interest are determined by the properties of primary fission fragments, whose subsequent decay is typically modeled using statistical reaction theories. A primary goal of fission theory is therefore to provide microscopic predictions of these initial fragment conditions.
We present a framework that combines joint angular momentum and particle-number projection with time-dependent configuration mixing to calculate angular momentum distributions of primary fission fragments. Focusing on neutron-induced fission of 235U and 239Pu, we report the first microscopic predictions of angular momentum distributions for all experimentally observed fragments.
Our results show a pronounced sawtooth pattern in average angular momentum versus fragment mass, consistent with recent measurements. Significant variations along isobaric chains indicate that commonly used empirical formulas may be insufficiently accurate. We also find a strong correlation between fragment angular momentum and deformation at scission, and a weak correlation between the angular momenta of the two fragment partners. The preliminary analysis indicates that these microscopic distributions can be used instead of phenomenological ones to reproduce fission spectra without additional adjustable parameters.
These results can help inform widely used phenomenological models and pave the way toward fission modeling based on robust microscopic inputs.
